When the disk drive stops operating, the signal conversion element oscillating arm (hereinafter simply called an oscillating arm) mounted with a signal conversion element is unloaded from a data-recorded zone and moved to a specified zone (parking zone) on the recording medium or moved to a specified position near the outer periphery of the recording medium at which the signal conversion element is in non-contact with the surface of the recording medium to be held there. That is, when the disk drive is not operating, the oscillating arm is held at a specified shunt (parking) position. Further, an oscillating arm holding mechanism or gripping mechanism for holding or gripping the oscillating arm at its shunt position is employed in order to prevent fatal problems from occurring, when the disk drive is given external shocks during its stop mode, such as the oscillating arm moving to the data recorded zone of the recording medium from the shunt position, causing damage to the surface of the recording zone of the recording medium due to collision of the signal conversion element and the recording medium, or the surface of the data-recorded zone of the recording medium being damaged due to the signal conversion element sliding thereon as the operation is started with the element being in contact with the data recorded zone when moved to the data recorded zone, or other component parts of the disk drive colliding with the oscillating arm, causing damage to the component parts and the oscillating arm.
An example of a conventional disk drive having an oscillating arm holding mechanism or gripping mechanism will be described in the following.
First, as to a disk storing device having an oscillating arm holding mechanism, the configuration proposed is such that an actuator (corresponding to the oscillating arm) being a voice coil motor (hereafter called VCM) comprises an actuator arm provided with a conversion head (corresponding to the signal conversion element) at one end and a coil at the other end thereof, of which an iron piece is attached to a projection integrally disposed at the other end, and also, a permanent magnet fixed in a housing opposite to the iron piece disposed on the actuator arm, and an actuator arm holding mechanism with the iron piece arranged on the actuator arm and the permanent magnet fixed in the housing.
In such a configuration, when the disk storing device stops operating, a current is supplied to the coil of the VCM, and the actuator arm is operated to move to a specified shunt position, then the iron piece is attracted by the permanent magnet as it approaches the specified shunt position, which is thereby able to fix the actuator arm at the shunt position. And in that condition, the actuator arm will not be moved even when an external force is given thereto because it is held by magnetic attraction, and thereby, the data on the data recorded zone of the recording medium and the actuator are prevented from accidental movement of the conversion head and the actuator arm (for example, refer to Japanese Patent Publication No. JP2803693, P3 and FIG. 1).
Also, as to a disk storing device having an oscillating arm gripping mechanism, the configuration proposed is such that there is provided an actuator arm gripping mechanism, the same as in the above example of a disk storing device having an oscillating arm holding mechanism, and further, it comprises an actuator arm gripping mechanism formed of a lock means and solenoid coil, wherein the actuator arm gripping mechanism is further resilient so as to vertically engage the actuator being the VCM, and a spring plate with a vertical stress is vertically moved according to the movement of an iron plunger with a current supplied to the solenoid coil, and under the plunger is arranged a magnet as the first magnetic field feeding means having the first magnetic force, and there above is arranged a VCM yoke as the second magnetic field feeding means having the second magnetic force, and when the first current is supplied to the solenoid coil, a magnetic force to push up the plunger is generated to move the spring plate upward, and also, when the second current different from the first current is supplied, a magnetic force to push down the plunger is generated to move the spring plate downward. Also, the spring plate is fixed at the lower side by the first magnetic force of the magnet having a downward magnetic force greater than the vertical stress of the spring plate, and also, the spring plate is attracted upward and fixed at the upper side by the second magnetic force of the VCM yoke in addition to the upward stress of the spring plate.
In such a configuration, when the disk drive is operated, the plunger is attracted toward the magnet by the first magnetic force, and further, the spring plate is pressed down by the plunger, thereby securing the spring plate so as to be fixed in an unlocked state at a height so that the spring plate does not block the movement of the actuator. Also, when the disk drive is stopped, the actuator is moved to a specified position (corresponding to the shunt position), and the first current that is greater than the difference between the first magnetic force of the magnet and the stress of the spring plate and is also able to generate an upward magnetic force is supplied to the solenoid coil, thereby moving the spring plate upward, and thus the spring plate is moved to the upper side and fixed in a locked state. In this case, the current is supplied to the solenoid coil only when the state is shifted from an unlocked state to a locked state or from a locked state to an unlocked state, and when the spring plate is fixed at the lower side or upper side in an unlocked state or a locked state, the solenoid coil is not supplied with current. When the disk drive is stopped, the magnetic attraction by the iron piece and permanent magnet and the spring plate are fixed at the upper side in a locked state, locking the actuator at the shunt position, and thereby, the actuator can be secured horizontally and vertically, and it is possible to prevent the actuator from being moved by shocks (for example, Japanese Patent Laid-Open Application No. JP08-221915, P4, P5, FIG. 1, FIG. 2 and FIG. 4).
Also, as an another example of a disk storing device having an oscillating arm gripping mechanism, the configuration proposed is such that the actuator is rotatably disposed for rotation about the oscillation axis, comprising a head arm and a coil arm which are arranged opposite to each other with the oscillation axis therebetween. The disk drive thus configured is characterized as in the following.
(1) The head arm is formed of a carriage arm and a suspension arm, and the suspension arm has a tab formed with a projection for shunting to the ramp block, and a read and/or write head mounted with a signal conversion element is disposed near there.
(2) Also, the coil arm mounted with a voice coil on the inner surface is formed of an outer arm and an inner arm.
(3) The ramp block and the inertia mechanism which are disposed at the shunt position of the actuator are housed in an enclosure.
(4) The ramp block threaded to the enclosure has a plurality of ramps protruded horizontally from the side of the ramp support, and the ramp has a composite plane including a first slope, a peak plane, a second slope, a bottom plate, and a third slope.
(5) The inertia mechanism comprises an inertia lever capable of oscillating about the oscillation axis, a latch lever capable of oscillating about other oscillation axis, and a spring for holding the latch lever at the arm release position. And at the inertia moments of the inertia lever and the latch lever around the respective oscillation axes, the inertia moment of the inertia lever is greater than that of the latch lever.
(6) The inertia lever includes an inertia arm and a balance arm on which a first fitting projection for engaging the latch lever at the first fitting portion and a second fitting projection for engaging at the second fitting portion are formed.
(7) The latch lever includes a latch arm and a sub-arm on which two spring fitting projections, positioning projection, and latch projection for engaging the action side end of the spring are formed. The positioning projection serves to determine the actuator release position of the latch lever and the actuator latch position. The latch projection serves to latch the actuator by engaging the tip of the inner arm of the actuator when the latch lever moves to the actuator latch position.
(8) The actuator lock mechanism is formed of the ramp block and the inertia latch mechanism.
Regarding the configuration having these characteristics, when the disk drive is in non-operation mode, the actuator is unloaded to the shunt position, and the tab of the suspension arm is held on the bottom plane of the ramp, and when the shock is very fine, the tab projection of the suspension arm climbs the second slope or the third slope of the ramp to attenuate the oscillation energy of the head arm, thereby suppressing the movement of the head arm and preventing the head arm from moving from the shunt position to the disk side or to the side opposite thereto, which functions as an actuator holding mechanism for holding the head arm at the shunt position. Also, in the operation of the inertia latch mechanism when a shock is given to the disk drive in non-operation mode, in case the actuator is given torque to oscillate counterclockwise due to an external shock, the inertia lever and the latch lever are given torque to rotate counterclockwise about the respective oscillation axes, and when the torque acting on the inertia lever is greater than the torque due to the shock on the latch lever and the resultant torque due to the spring torque to turn the latch lever clockwise about the oscillation axis, then the inertia lever turns counterclockwise irrespective of the direction of the torque acting on the latch lever, and at the first fitting portion, the latch lever is pulled by the first fitting projection to oscillate the latch lever counterclockwise, and the latch projection of the latch arm engages the tip of the inner arm coming from the shunt position, thereby latching the actuator. After that, the tab of the actuator is pushed back to the bottom plane of the ramp by the action of the second slope of the ramp, disengaging the inner arm tip and the latch projection, and then the latch arm returns to the actuator release position by the action of the spring. Also, when the actuator is given torque to oscillate clockwise due to external shocks, the inertia lever and the latch lever are given torque to oscillate clockwise about the respective oscillation axes, and then the latch lever is always subjected to torque to turn clockwise about the oscillation axis by the action of the spring in addition to the torque due to the shocks. At the second fitting portion, in case the torque acting on the inertia lever is greater than the resultant force of the torque due to shocks given to the latch lever and the torque by the action of the spring, the latch lever is pushed by the second fitting projection at the second fitting portion, oscillating the latch lever counterclockwise, and the latch projection of the latch arm bumps against the crush stop made from a resilient material to restrict the oscillation range of the actuator, thereby engaging the tip of the inner arm rebounded counterclockwise and causing the actuator to be latched. The torque due to shocks acting upon the inertia lever is greater than the torque given to the latch lever due to shocks, and the inertia moment of the inertia lever is set greater than the inertia moment of the latch lever in order to attain the oscillation in the direction of the inertia lever's torque due to shocks, and the oscillating distance of the latch projection from the release point to the latch point, the position of the latch point, and the distance from the latch projection to the oscillation axis are set so that the latch projection moves to the latch point before the tip of the inner arm moves from the shunt point to the latch point, and thus the actuator is latched at the shunt position, then the actuator is locked, thereby preventing the head arm and the read and/or write head from getting into the space where a disk is arranged. (For example, refer to Japanese Patent Laid-Open Application No. 10-302418, P4, P5, FIG. 1, FIG. 2; No. 2002-206356, P5˜6, FIG. 1).
However, in the holding mechanism of the actuator used for a disk storing device having a conventional oscillating arm holding mechanism as described above, when the disk storing device is stopped, the actuator arm is secured at the shunt position of the actuator by the attraction of the iron piece and the permanent magnet fixed in the housing which are disposed on the actuator arm. In the case of an actuator holding mechanism with such a configuration, the shock resistance is relatively high when a shock is given in the same direction as the rotating direction of the actuator, but the shock resistance is relatively low when a great shock is given for a short time or the shock given includes a vertical component as against the rotating direction of the actuator. Therefore, there arises a problem that it is unable to display sufficient holding function against shocks. Also, an iron piece and permanent magnet are necessary to hole the actuator at the shunt position, resulting in increase of the number of component parts and the cost of the device.
Also, in the case of an actuator gripping device having a conventional oscillating arm holding mechanism as described above, the actuator gripping device is configured in that the actuator is gripped at the shunt position in order to prevent the actuator at the shunt position from moving to the data recorded zone of the recording medium when a relatively great shock is given to the device. Particularly, in the example having an actuator gripping device formed of a lock means and solenoid coil, the actuator gripping device comprises an iron piece disposed on the actuator arm, a permanent magnet disposed in the housing, a spring plate for gripping the actuator, a magnet for fixing the spring plate at the lower side, a plunger for vertically moving the spring plate, and a solenoid coil for vertically moving the plunger. And when the disk drive is stopped, the actuator is moved to the shunt position, and the spring plate is moved upward along the vertical movement of the plunger, thereby locking the spring plate and locking the actuator at the shunt position. In this way, it is resistant against relatively great shocks, but when subjected to very great shocks in the same direction as the moving direction of the plunger, it is necessary to set the upward stress of the spring and the second magnetic force of the VCM yoke high enough to resist the shocks in order to maintain the locked state of the spring plate. Accordingly, for achieving the purpose of moving the plunger downward against the great resultant force of the upward stress of the spring plate and the second magnetic force of the VCM yoke and for unlocking the spring plate, it is necessary to generate a great magnetic force by applying a high level of current to the solenoid coil, and consequently, the solenoid coil has to be increased in size and there should be provided a space for arranging the component parts of the actuator gripping device to lock the actuator at the shunt position, making it difficult to reduce the size of the disk drive. Further, a large number of parts are required for setting up the actuator mechanism, resulting in increase of the cost of the device.
Also, in the disk drive comprising an actuator rotatably disposed about the oscillation axis, and a head arm and a coil arm which are arranged so as to be opposed to each other across the oscillation axis, the inertia latch mechanism is configured with an inertia lever, latch lever and spring, and when the disk drive in non-operation mode is given a relatively great shock, the inertia lever rotates, causing the latch lever to turn counterclockwise irrespective of the direction of torque acting upon the latch lever, and the latch projection of the latch arm to engage the tip of the inner arm at the coil arm of the actuator coming from the shunt position, and thereby, the actuator is latched. And to achieve the purpose, the inertia moment of the inertia lever is set greater than the inertia moment of the latch lever. In the case of an actuator gripping device based on a configuration having such an inertia latch mechanism, the blind zone against shocks can be can be reduced, improving the reliability of the actuator gripping device, but many parts are necessary for configuring the inertia latch mechanism and also a space is required for arranging such parts, resulting in increase of the cost of the device and causing hindrance to the size reduction.
The present invention is intended to solve the above problems, and the object of the invention is to provide an actuator gripping device having a very simple configuration and excellent impact resistance, and a disk drive provided with the device.